Composition for and method of pumping concrete

ABSTRACT

A composition for and a method of promoting the flow of a concrete slurry through a pump and a conduit is provided. The composition is a dry particulate mixture comprised of a water soluble, inorganic material and a solvatable, organic polymer. The composition, when mixed with a suitable quantity of water, is useful in a method of priming a pump used to pump a concrete slurry. The composition, when mixed with a concrete slurry, is useful to improve the flow of the slurry through a conduit.

This application is a division of application Ser. No. 08/282,879, filedJul. 29, 1994, now U.S. Pat. No. 5,443,636.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention broadly relates to concrete. It further relates tomaterials added to concrete or otherwise employed therewith to adjustthe properties or to enhance and/or to facilitate the use thereof. Thisinvention further, and more specifically, relates to an additivecomposition for and a method of promoting the flow of concrete andparticularly the flow thereof through a pump and a conduit.

2. Description of the Prior Art and Problems Solved

It is well known that concrete is useful as a basic and highly versatilematerial of construction. The versatility of concrete stems, at least inpart, from the fact that concrete initially occurs in a fluid condition,which, after a period of time, converts into a monolithic solidcondition. In the fluid condition, concrete, being comprised of discretesolids dispersed in water, has little or no compressive strength; it canbe pumped; and it will flow into and assume the shape of a container,referred to in the art as a form. After a period of time, the fluidconcrete sets into the dense, rigid, monolithic solid condition havingthe shape of the form and exibiting substantial compressive strength.

For purposes of this disclosure, the fluid condition of concrete, whichis referred to in the concrete construction art as "plastic concrete,"featuring the dispersion of solids in water, is referred to herein as aconcrete slurry, and the monolithic solid condition of concrete isreferred to herein as set concrete. The dispersed solids are usuallycomprised of hydraulic cement and aggregate wherein the aggregateordinarily, but not always, consists of graded coarse aggregate, i.e.rock, mixed with graded fine aggregate, i.e. sand.

It is known that a concrete slurry can be prepared for use in onelocation, which can be remote from the place of its intended use, andthen conveniently transported by known means, such as in a truck, to theplace of its intended use. It is also known that a concrete slurry canbe prepared while being transported to the intended place of use. Atruck ordinarily employed to transport a concrete slurry is referred toin the art as a ready mix truck.

When a concrete slurry is delivered to the intended location of use, itis known that it can be caused to flow by gravity or by pumping into aform where, because of its fluid condition, it conforms to the shape ofthe form. After the concrete slurry is in the form it is permitted toremain undisturbed therein for a period of time sufficient to enable thecementious material to hydrate to thereby produce the set concrete.

One of the problems involved in the placement of a concrete slurry,which is the problem specifically addressed in this disclosure, concernsthe potential difficulty of causing the slurry to flow through aconduit. In this regard, it is sometimes necessary, or otherwiseconvenient, to place the slurry in the desired form by pressuring it, bymeans of a pump, through a conduit over a distance to the desired form.However, due to the nature of a concrete slurry, it has sometimes beenfound essential, in order to initiate movement of a slurry to andthrough the pump and conduit, to first fill the pump used to pressurethe slurry through a conduit with a fluid which is easily pumped andwhich will lubricate the conduit itself, followed by pumping such fluidahead of the slurry. The process of filling a pump with a fluid which iseasily pumped followed by pumping in order to initiate slurry movementis referred to as priming.

It is known that a concrete slurry which contains coarse aggregate whichis irregular in size and/or shape and/or which contains solids which arenot uniformly dispersed in the water phase and/or which has a low volumeratio of hydraulic cement to total concrete slurry cannot be pumpedeasily, if at all, unless the pump is first primed.

A concrete slurry having a low volume ratio of hydraulic cement toslurry, which is known in the art as a low strength mix, does notcontain sufficient hydraulic cement to lubricate the pump, conduit andaggregate to enable satisfactory slurry flow. It is believed that a lowvolume ratio of hydraulic cement to slurry is one featuring about 10volume parts or less of hydraulic cement per 100 volume parts ofconcrete slurry.

The flow of a concrete slurry which includes coarse aggregate which isnot of proper size gradation, as set out in ASTM C33-92a (Std. Spec. forConcrete Aggregates), or which is angular or broken or in which solidsare not uniformly dispersed in the water phase or any combinationthereof will tend to be at least impeded and perhaps even will becompletely blocked and will, accordingly, require the application ofpriming.

It is highly desireable that the combination of aggregate, water andhydraulic cement act together in the flowing slurry to produce acondition, referred to in the art as the ball bearing effect, whichresults in the smooth and uninterupted flow of the concrete slurry.

Coarse and fine aggregates often used in the formulation of a concreteslurry are not the type which will produce the ball bearing effectprincipally due to the fact that the more desireable type of coarseaggregates, i.e. aggregates which are round, smooth, unbroken and ofproper size gradation, are in short supply or are simply not availablein view of various factors including the high demand for concreteconstruction and decreasing convenient sources of such aggregates.Accordingly, the need for improved compositions for and methods ofpriming a concrete pump and lubricating a conduit to ease slurry flow iscurrent and will continue to increase with the passage of time.

The prior art has addressed the problem of priming a concrete slurrypump by employing methods featuring the use of two differentcompositions, one of which is called a "priming grout mix" and thesecond of which is called a "priming slurry." The methods of priming aconcrete slurry pump with either a priming grout mix or a primingslurry, as heretofore employed, are similar and suffer a commondisadvantage. The disadvantage originates from the fact that theconcrete slurry being pumped is not compatible and cannot be admixedwith either one of the prior art priming compositions because any suchadmixture adversely affects the strength of the set concrete.Accordingly, when employing either one of the prior art methods, thedelivery end of the conduit cannot be placed in the form until all ofthe priming composition has exited therefrom in order to avoid anyadmixing of slurry and priming composition.

Because the prior art compositions cannot be admixed with the concreteslurry, as explained above, the priming compositions must be directed toand placed in a separate location to enable hydration and subsequentdisposal thereof. Accordingly, a waste disposal and potentialenvironmental hazard inherently accompanies the use of prior art primingcompositions.

Thus a problem to be solved is to devise a composition for and a methodof priming a concrete slurry pump which will not only permit a slurry tobe successfully pumped, but which will also avoid the waste disposal andenvironmental problems associated with methods currently employed.

A priming grout mix usually consists of concrete sand, hydraulic cementand water in the weight ratio of 10 to 2 to 1, respectively. In typicalpractice about one-half cubic yard of priming grout mix is placed in aready mix truck which then transports the mix to the location of theconcrete slurry pump, which is ordinarily a positive displacement pump;the mix is there employed to prime the pump in order to cause a concreteslurry to move through the pump and conduit to the desired form. In theexample just cited, one-half cubic yard of priming grout mix includesabout 1500 pounds of sand, 300 pounds of dry cement and 150 pounds ofwater. In view of the fact that a ready mix truck ordinarily holds atleast about 8 cubic yards of material it is apparent that a truckemployed to transport a priming grout mix is dramatically under utilizedin that it is solely used to transport a material which cannot be addedto the concrete slurry.

A priming slurry typically consists of one bag of hydraulic cementdispersed in 6 or 7 gallons of water. As used herein, a bag of cementweighs about 94 pounds; since a gallon of water weighs about 8.33pounds, the weight ratio of cement to water in a typical priming slurryis an amount in the range of from about 1.6 to about 1.9 pounds ofcement per pound of water. In practice about one-half of the requiredcement and water is thoroughly mixed and added to an apparatus, referredto in the art as a hopper, which is in direct fluid communication withthe suction side of the concrete pump, thereafter the balance of thecement and water is thoroughly mixed and added to the hopper prior tothe initiation of pumping.

Although use of a priming slurry does not involve an extra ready mixtruck, as is required in the case of a priming grout mix as describedabove, it is required that extra bags of dry cement be transported tothe pump location to enable on-site preparation of the priming slurry.

DISCLOSURE OF INVENTION 1. Summary of the Invention

It has now been discovered that a composition comprised of a watersoluble, inorganic, alkaline material in combination with a solvatable,organic, polymeric material, when mixed with a quantity of watersufficient to dissolve the alkaline material and solvate the polymericmaterial, is broadly useful to improve the fluid characteristics of aconcrete slurry. In one specific aspect the composition of thisinvention finds application in a method of pressuring, such as in apump, a concrete slurry through a conduit. In a second specific aspectthe composition of this invention finds application in a method ofimproving the ability of a concrete slurry to flow in any channel, suchas in a closed conduit or in an open trough, either by gravity or bysome externally applied mechanical means.

The composition, when mixed with a sufficient quantity of water asmentioned above, forms a fluid, referred to herein as a sol, having analkaline pH, preferably in the range of from about 11 to 12, and havinga concentration in the range of from about 0.5 to about 3.5, preferablyfrom about 1 to about 3 and still more preferably from about 1 to about2 pounds of the composition per 100 pounds of sol. The preferred fluidcontains about 1.2 pounds of composition per 100 pounds of sol. Theabove concentrations can also be expressed in terms of pounds of waterper pound of composition wherein water is present in the range of fromabout 27 to about 210, preferably from about 35 to about 100 and stillmore preferably from about 50 to about 100 pounds of water per pound ofcomposition. The preferred fluid contains about 83.3 pounds of water perpound of composition.

The above concentrations are stated in terms of pounds of compositionper 100 pounds of sol, or as pounds of water per pound of composition.However, it is customary, and consequently preferred, in the art toexpress the concentration of the composition in terms of pounds ofcomposition per gallon, or gallons, of water. It is still furtherpreferred, as is explained below, to express the usage, or dosage, ratesof the composition in units of 0.5 pound of composition per gallon, orgallons, of water, or per ready mix load of concrete slurry. It is to beunderstood, however, that the dosage rates disclosed herein produceconcentrations within the scope of the concentration weight ranges whichare disclosed above and set out in the appended claims.

The composition, which is sometimes referred to herein as an additivefor concrete and sometimes as the additive of this invention, whenemployed in the above mentioned method of pressuring a concrete slurrythrough a conduit, is referred to in the art as a priming aid, and whenemployed in the above mentioned method of improving the ability of aconcrete slurry to flow, is referred to in the art as a pumping aid. Forconvenience, the composition, especially when in the form of thealkaline sol, is broadly referred to herein by its perceived function asa lubricant. It is believed, as explained below, that the compositionalso functions to help reduce the loss of water from the concreteslurry.

The composition can be mixed with a concrete slurry without causing anydeleterious effect on the slurry or the set concrete. Thus, use of theadditive of this invention avoids the environmental problems of priorart priming compositions, as mentioned above, because use of theadditive of this invention does not create a disposal problem in thatthe composition can be mixed with the concrete slurry.

The quantity of the composition of this invention required for use is sosmall, that use of separate ready mix trucks devoted solely totransportation of the composition is not required. In this regard whenthe composition is used as a priming aid, only about 0.5 pound ofcomposition per five gallons of water, i.e. about 41.65 pounds of waterper 0.5 pound of additive, is sufficient to prime a pump used topressure a concrete slurry through about 100 feet of a five-inchdiameter conduit.

When the composition is used as a pumping aid, about 0.5 to about 3.0pounds of composition per ready mix load of concrete slurry is requiredto adequately lubricate the slurry through conduit normally employed inthe art. A ready mix load of concrete slurry for purposes of thisdisclosure is defined to be about eight cubic yards which has a weightin the range of from about 3240 to about 82080 pounds and preferably inthe range of from about 30,240 to about 32,400 pounds. Accordingly, thequantity of composition, when used as a pumping aid, is an amount in therange of from about 1 pound per 1000 pounds to about 1 pound per 165000pounds, preferably in the range of from about 1 pound per 10000 poundsto about 1 pound per 100000 pounds and still more preferably in therange of from about 1 pound per 20,000 pounds of concrete slurry toabout 1 pound per 65,000 pounds of concrete slurry.

2. Description of the Preferred Embodiments

The composition of this invention, a dry, particulate material, iscomprised of a water soluble, inorganic, alkaline material incombination with a solvatable, organic, polymeric material which, whenmixed with a quantity of water sufficient to dissolve the alkalinematerial and solvate the polymeric material, is broadly useful toimprove the fluid characteristics of a concrete slurry. Theconcentration of said alkaline material in the composition is an amountin the range of from about 40 to about 99, preferably from about 60 toabout 90 and still more preferably from about 70 to about 85 parts byweight of said alkaline material per 100 parts by weight of saidcomposition.

The concentration of said polymeric material in said composition is anamount in the range of from about 1 to about 60, preferably from about10 to about 40 and still more preferably from about 15 to about 30 partsby weight of said polymeric material per 100 parts by weight of saidcomposition.

The composition of this invention, to be useful as contemplated herein,must be mixed with a quantity of water sufficient to dissolve thealkaline material and to solvate the polymeric material to thereby formthe above referred to alkaline sol. In this regard, when the compositionis used as a priming aid, all of the composition to be employed can befirst mixed in a container with a quantity of water sufficient to formthe sol, the sol can then be placed in a vessel which is in fluidcommunication with the suction side of the concrete pump and then thesol is pressured by the pump from the vessel into and through a conduitto a form. The vessel into which the sol is placed and from which thesol is pumped is referred to in the art as a hopper. While the sol isbeing pressured into the conduit from the hopper, and at least beforeall of the sol is pumped from the hopper, the concrete slurry to bepumped is added to the hopper such that a final portion of the sol is incontact with the initial portion of the concrete slurry whereby the solprecedes the slurry through the pump and conduit to the form. While notintending to be bound by a particular theory of operation, it isbelieved that the sol and concrete slurry do not substantially intermixone with the other, and that the sol, instead, moves in a cohesive unit,i.e., a plug, through the pump and conduit ahead of the concrete slurrywhile forming a thin film of the sol on the functioning parts of thepump and on the interior walls of the conduit to thereby lubricate thepump and conduit so as to ease the movement of the slurry therethrough.It is further believed that the film of sol also acts, indirectly, as ahydration aid in that it helps prevent the loss of water, needed tocompletely hydrate the hydraulic cement, from the concrete slurry to theconduit. In an alternative and preferred method of operation, thecomposition can be mixed with the water directly in the hopper insteadof in a separate container which is thereafter added to the hopper.

Thus, by this invention, there is provided a method of pressuring aconcrete slurry through a conduit, the method being comprised of thesteps of introducing a fluid composition into a chamber; placing thechamber in fluid communication with the inlet end of the conduit;applying pressure to the fluid composition in the chamber in an amountsufficient to cause the fluid composition to flow from the chamber intoand through..the conduit to the outlet thereof; and, thereafter, whilecontinually applying the pressure, introducing the concrete slurry intothe chamber such that the final portion of the fluid composition iscontacted by the initial portion of the slurry whereby the concreteslurry is pressured into and through the conduit to the outlet.

The fluid composition is comprised of an additive material mixed withwater, the additive material being comprised of a water soluble,inorganic, alkaline material and a solvatable, organic polymericmaterial. The concentration of the alkaline material in the additive isan amount in the range of from about 40 to about 99 parts per 100 partsby weight of the additive, the concentration of the polymeric materialin the additive is an amount in the range of from about 1 to about 60parts per 100 parts by weight of the additive. The water is present inthe fluid composition in an amount sufficient to dissolve the alkalinematerial and solvate the polymeric material.

When the composition is used as a pumping aid, it is added directly to aconcrete slurry and mixed therewith for a time sufficient to obtain auniform dispersion of the composition in the slurry. It is not requiredthat additional water also be added to the slurry, because water in theslurry is present in an amount sufficient to dissolve the alkalinematerial and solvate the polymeric material without depriving the Slurryof water required to completely hydrate the cement. A uniform dispersioncan be obtained by mixing the composition with a concrete slurry in aconventional ready mix truck. It is believed that about 0.5 to about 1.5and upto about 3.0 pounds of composition can be uniformly dispersed ineight cubic yards of concrete slurry in a ready mix truck in a time ofabout 5 to about 7 minutes. It is believed that the viscous nature ofthe sol not only helps to lubricate the solids in the slurry to therebypromote the ball bearing effect referred to previously, but also helpsto prevent water loss and solids separation to thereby promote completehydration of the hydraulic cement.

As a pumping aid the composition of this invention functions as anadditive for a concrete slurry which enables, improves, or at leastenhances, the ability of the slurry to flow. Thus by this inventionthere is provided an improved method of formulating a flowable concreteslurry consisting essentially of the steps of mixing solid ingredientscomprised of hydraulic cement and aggregate with water for a timesufficient to uniformly disperse the solid ingredients in the water tothereby formulate said concrete slurry; wherein the improvement consistsin the steps of adding to and mixing with the concrete slurry acomposition comprised of a water soluble, inorganic, alkaline materialand a solvatable, organic polymeric material in an amount in the rangeof from about 1 pound of composition per 1,000 pounds to about 1 poundof composition per 165,000 pounds of concrete slurry. The concentrationof the alkaline material in the composition is an amount in the range offrom about 40 to about 99 parts per 100 parts by weight of compositionand the concentration of the polymeric material in the composition is anamount in the range of from about 1 to about 60 parts per 100 parts byweight of the composition.

It should be apparent from the above that the composition of thisinvention can be employed in any given placement operation as both apumping aid and as a priming aid, in that addition of the compositiondirectly to the slurry together with mixing provides the slurry withinternal lubrication and water loss control, while addition of thecomposition to the pump provides the slurry with external lubricationand water loss control.

As previously mentioned, it is the practice in the art to express thequantity of composition to be utilized as a priming aid in terms ofpounds of composition per gallon of water in this connection thecomposition is preferably employed in field operations prepackaged in0.5 pound quantities. Accordingly, 0.5 pounds of a preferred blend ofthe composition of this invention can be placed in a water soluble bag,a specified number of such bags are then added to a specified number ofgallons of water, the bags and water are then mixed and allowed to setfor a period of time to yield viscosity to thus produce the desired sol.

In one preferred embodiment one water soluble bag containing 0.5 poundsof a preferred composition of this invention can be mixed with fivegallons of water to produce a priming aid which will treat about 100feet of five-inch diameter conduit. This fluid can be easily preparedfor use at the location of the concrete pump by merely mixing the bagand water in the hopper for about one minute followed by at least about5 minutes of set time to permit the bag to dissolve and release thecomposition and permit the sol thereby produced to yield satisfactoryviscosity. Pumping can proceed at the termination of the set time.

Water soluble bags found to be particularly useful herein are disclosedand claimed in U.S. Pat. No. 4,961,790 to Smith et al and in U.S. Pat.No. 5,120,367 to Smith et al.

It is not a requirement of the broad aspect of this invention that thecomposition of this invention be used in prepackaged water soluble bags,but use of such bags in actual field practice greatly simplies primingand pumping operations encountered in the field.

The term "solvatable, organic polymeric material," as used herein, meansand includes a wide variety of natural, modified natural, and synthetichydrophilic polymers which either dissolve in water or which at leastform colloidal dispersions in the presence of water wherein the effectof such solvation is to produce an increase in the viscosity of thewater. Such materials are generally characterized as having highmolecular weight and are sometimes referred to in the art as "aqueousgelling agents" and sometimes as "aqueous viscosifiers."

The polymeric materials, as defined above, have molecular weights in therange of from about 60,000 to about 4,000,000 and higher and includepolysaccharides, examples of which include galactomannan gums andglucomannan gums, which are naturally occurring; cellulose derivatives,which is cellulose modified by reaction with hydrophilic constituents;galactomannan and glucomannan gums which have been modified by reactionwith hydrophilic constituents; and synthetic hydrophilic polymers.

Examples of hydrophilic constituents include hydroxyalkyl groups,carboxyalkyl groups and mixed hydroxyalkyl and carboxyalkyl groups toform ether derivatives. Other constituent groups which lend hydrophilicproperties to polymers include cis-hydroxyl, hydroxyl, carboxyl,sulfate, sulfonate, amino and amide groups.

Guar gum, locust bean gum, karaya gum, carboxymethylguar,hydroxyethylguar, hydroxypropylguar, carboxymethylhydroxyethylguar,carboxymethylhydroxypropylguar, carboxymethylcellulose,carboxymethylhydroxyethylcellulose, hydroxyethylcellulose, starches,alginates and carrageenans are examples of natural and modifiedpolymeric materials useful herein.

Examples of synthetic hydrophilic polymers and copolymers useful in thecomposition of this invention include polyethylene oxide, polypropyleneoxide, polyacrylate, polymethacrylate, polyacrylamide,polymethacrylamide and copolymers thereof, maleic anhydride/methylvinylether copolymers, polyvinyl alcohol, polyvinylpyrrolidone,polyvinylacetate, copolymers of acrylamide and 2-acrylamido,2-methylpropane sulfonic acid and copolymers of N,N-dimethylacrylamideand 2-acrylamido, 2-methylpropane sulfonic acid.

The solvatable, organic polymeric material useful herein can be either asingle polymer or copolymer or a mixture of polymers and copolymers. Apreferred such mixture features the presence of a modified naturalpolymer as mentioned above and a synthetic hydrophilic polymer asmentioned above wherein the weight ratio of synthetic polymer tomodified natural polymer is an amount in the range of from about 1 to 1to about 2 to 1.

Modified natural polymers preferred for use herein are cellulose ethers,such as carboxymethylcellulose and hydroxyethylcellulose andparticularly those having a molecular weight of less than about 100,000.Synthetic hydrophilic polymers preferred for use herein arepoly(ethylene oxide) resins having a molecular weight of about4,000,000. Examples of such resins are sold under the trademark POLYOXby Union Carbide Corporation.

Since polyethylene oxide, when in water solution, is referred to aspoly(ethylene ether) glycol or, more simply, as polyethylene glycol,such compounds are within the scope of this invention.

The inorganic, alkaline material useful herein includes alkali metalhydroxides, carbonates and bicarbonates, preferably the alkali metalcarbonates and still more preferably sodium carbonate.

The composition preferred for use herein as a priming aid and as apumping aid is a dry blend consisting essentially of an alkali metalcarbonate, polyethylene oxide and a cellulose ether wherein the alkalimetal carbonate is present in the composition in an amount in the rangeof from about 80 to about 90 parts per 100 parts by weight of thecomposition with the balance of the composition being selected frompolyethylene oxide and a cellulose ether in various weight proportions,as previously stated, wherein the total quantity of the polymericconstituent present in the composition is an amount in the range ofabout 10 to about 20 parts per 100 parts by weight of the composition.The most preferred composition contains about 84.375 parts by weightsodium carbonate, about 9.375 parts by weight polyethylene oxide andabout 6.25 parts by weight hydroxyethycellulose.

The most preferred composition is conveniently, and thus preferably,employed, in accordance with the disclosed priming and pumping methodsof this invention, in 0.5 pound quantities, prepackaged in water solublebags, as described above.

The term "hydraulic cement," as used herein, means all inorganiccementitious materials of known type which comprise compounds ofcalcium, aluminum, silicon, oxygen, and/or sulfur which exhibit"hydraulic activity," that is, which set solid and harden in thepresence of water. Cements of this type include common Portland cements,fast setting or extra fast setting, sulfate resistant cements, modifiedcements, alumina cements, high alumina cements, calcium aluminatecements and cements which contain secondary components such as fly ash,pozzolana and the like.

Portland cements are classified by the American Society of TestingMaterials (ASTM) into five major types identified by Roman Numerals I,II, III, IV and V and by the American Petroleum Institute into at least9 categories identified by the letters A, B, C, D, E, F, G, H and J. Theclassifications are based on chemical composition and physicalproperties.

The term "hydraulic cement," as used herein, also includes a materialidentified as slag and mixtures thereof with Portland cement.

"Slag," as used herein, means a granulated, non-crystalline, glassymaterial having a particle size in the range of from about 1 to about100 microns which exhibits hydraulic activity. Slag is a blast furnace,by-product formed in the production of cast iron and is broadlycomprised of the oxidized impurities found in iron ore.

The hydraulic cement useful herein can also include small particle sizecement which consists of discrete particles of hydraulic cement havingdiameters no larger than about 30 microns. Small particle size cement ismore fully discussed in Ewert, et al., U.S. Pat. No. 5,121,795.

The quantity of water employed in the formulation of a concrete slurryuseful herein is dependent upon the particle size of the cementemployed. Thus, the quantity of water employed is an amount in the rangeof from about 0.25 to about 5.0 pounds of water per pound of dryhydraulic cement. For cements having a particle size of less than about45 microns the preferred water to cement ratio is in the range of fromabout 1.0 to about 2.0 pounds of water per pound of cement. For cementswhich have a particle size greater than about 45 microns the preferredwater to cement ratio is in the range of from about 0.3 to about 0.6pounds of water per pound of dry cement.

The quantity of aggregate employed in the formulation of a concreteslurry useful herein is an amount in the range of from about 3 to about15 pounds of aggregate per pound of dry cement. The aggregate may beentirely coarse aggregate or entirely fine aggregate or any blendthereof.

EXAMPLES

The following examples are provided to illustrate the practice of theinvention as well as certain preferred embodiments thereof. The examplesshould not be construed as limiting in any way the spirit or scope ofthe invention and are not provided as such a limitation.

Example 1

Experiments were conducted to determine the effect of the additive ofthis invention on certain of the properties of concrete. Two slurrieswere prepared. The sole difference between them was that one,Formulation A, did not include the additive of this invention, but thesecond, Formulation B, did contain the additive of this invention. Thespecific recipes of Formulations A and B are provided in Table I, below.The ingredients were wet mixed, in accordance with recognized industrystandards, to obtain concrete slurries having solids uniformly dispersedin water.

The test results are provided in Tables II and III, below. Table IIreports the test results obtained on the concrete slurry. Table IIIreports the test results obtained on the set concrete.

                  TABLE I                                                         ______________________________________                                                         Formulation,                                                                  4 cubic yards                                                                   A       B                                                  Ingredient         pounds  pounds                                             ______________________________________                                        Portland Cement,   2256    2256                                               ASTM Type I.sup.1                                                             Fine Aggregate.sup.2                                                                             5036    5036                                               Coarse Aggregate.sup.2                                                                           6956    6956                                               3/4"                                                                          Lubricant.sup.3      0        0.5                                             Water              1128    1128                                               ______________________________________                                         Footnotes for Tables I, II and III:                                           .sup.1 Lone Star Cement Company.                                              .sup.2 Stand. Spec. For Concrete Aggregates ASTM C 3392a.                     .sup.3 Sodium carbonate 84.375%, polyethylene oxide 9.375%, Hydroxyethyl      cellulose 6.25%.                                                              .sup.4 ASTM C 23191b.                                                         .sup.5 ASTM C 40392.                                                          .sup.6 ASTM C 14390a                                                          .sup.7 ASTM C 3986                                                       

                  TABLE II                                                        ______________________________________                                        Slurry Data                                                                                  entrained.sup.4                                                Formula-                                                                             slump.sup.5                                                                           air       temperature, °F.                                                                  initial set.sup.5                         tion   inches  %         concrete                                                                              air  hours                                   ______________________________________                                        A      4       5.6       76      75   3.22                                    B      4.5     5.6       76      77   3.3                                     ______________________________________                                         Footnotes for Tables I, II and III:                                           .sup.1 Lone Star Cement Company.                                              .sup.2 Stand. Spec. For Concrete Aggregates ASTM C 3392a.                     .sup.3 Sodium carbonate 84.375%, polyethylene oxide 9.375%, Hydroxyethyl      cellulose 6.25%.                                                              .sup.4 ASTM C 23191b.                                                         .sup.5 ASTM C 40392.                                                          .sup.6 ASTM C 14390a                                                          .sup.7 ASTM C 3986                                                       

                  TABLE III                                                       ______________________________________                                                   Compressive Strength.sup.7, lb/in.sup.2                                       Test Age, days                                                     Formulation  1      3          7    28                                        ______________________________________                                        A            1500   2290       2860 4290                                      B            1580   2470       3130 4570                                      ______________________________________                                         Footnotes for Tables I, II and III:                                           .sup.1 Lone Star Cement Company.                                              .sup.2 Stand. Spec. For Concrete Aggregates ASTM C 3392a.                     .sup.3 Sodium carbonate 84.375%, polyethylene oxide 9.375%, Hydroxyethyl      cellulose 6.25%.                                                              .sup.4 ASTM C 23191b.                                                         .sup.5 ASTM C 40392.                                                          .sup.6 ASTM C 14390a                                                          .sup.7 ASTM C 3986                                                       

From the above results, as shown in Tables II and III, it is clear thatthe additive of this invention, identified as the lubricant in Table I,above, caused no detrimental effects on the workability, entrained aircontent, setting time or compressive strength of a concrete containingthe additive as compared with a concrete of identical recipe which didnot contain the additive.

With regard to the compressive strength data provided in Table III, itis noted that the strength data provided are the average resultsobtained of two or more break tests.

It is further noted that the lubricant employed in Formulation B, above,was a mixture of dry, particulate, ingredients, as described in footnote3, above, wherein the entire quantity thereof employed was contained ina water-soluble container which was added, as such, to and wet-mixedwith the balance of,the ingredients of Formulation B in a conventionalwet-mixer apparatus. The water soluble container employed is disclosedand claimed in U.S. Pat. No. 4,961,790 to Smith et al and in U.S. Pat.No. 5,120,367 to Smith et al.

Example 2

Tests were conducted on various compositions to determine thesuitability of the compositions as pumping aids and/or as priming aidsfor concrete slurries. The tests were conducted by mixing a quantity ofeach composition tested with five gallons (41.65 pounds) of potablewater to thus produce a fluid having a concentration in the range offrom about 0.19 to about 1.19 percent composition by weight of fluid.Each test fluid was prepared by manually stirring it for sixty secondsimmediately upon mixing the water and composition, then allowing it toset, undisturbed, for five minutes and thereafter manually stirring itfor an additional sixty second period. Each fluid was then placed in aFann viscometer (Model 35A, Rotor-Bob R1B1, with a 1" spring) andapparent viscosity readings were taken at shear settings of 600, 300,200 and 100 rpm at 77° F. Visual observations of the fluids were made.

The ingredients of the compositions tested are set out in Table IV,below. It is noted that composition A is water and is provided forcontrol purposes only. Compositions B, C, D, and E are examples of thecomposition of this invention.

The apparent viscosity test results and visual observations are set outin Table V, below.

It is noted that compositions B through J, below, were dry, particulate,materials wherein the entire quantity of each employed was contained ina water-soluble container which was added, as such, to and mixed withwater as described above. The water soluble container employed isdisclosed and claimed in U.S. Pat. No. 4,961,790 to Smith et al and inU.S. Pat. No. 5,120,367 to Smith et al.

                                      TABLE IV                                    __________________________________________________________________________              INGREDIENTS, percent by weight of composition                                 (pounds of ingredient)                                                        sodium polyethylene                                                                         hydroxyethyl                                                                          carboxyethyl                                  COMPOSITION                                                                             carbonate                                                                            oxide  cellulose                                                                             cellulose                                     __________________________________________________________________________    A         0      0      0       0                                             B         84.375 9.375  6.25    0                                                       (0.421875)                                                                           (0.046875)                                                                           (0.03125)                                             C         84.375 15.625 0       0                                                       (0.421875)                                                                           (0.078125)                                                   D         87.5   6.25   6.25    0                                                       (0.4375)                                                                             (0.03125)                                                                            (0.03125)                                             E         87.5   6.25   0       6.25                                                    (0.4375)                                                                             (0.03125)      (0.03125)                                     F         0      100.00 0       0                                                              (0.5)                                                        G         0      0      100.00  0                                                                     (0.5)                                                 H         0      60.00  40.00   0                                                              (0.046875)                                                                           (0.03125)                                             I         0      100.00 0       0                                                              (0.078125)                                                                           0       0                                             J         0      0      100.00  0                                                                     (0.078125)                                            __________________________________________________________________________

                  TABLE V                                                         ______________________________________                                                 FANN VISCOSITY                                                                @ specified rpm                                                      COMPOSITION                                                                              600    300    200  100  OBSERVATION                                ______________________________________                                        A          1      0.5    0    0    clear water, one                                                              phase, thin (very                                                             low viscosity)                                                                fluid                                      B          55     30     17   8    slick, slimy,                                                                 thick uniform                                                                 fluid, one phase                           C          60     40     31   19   same as B                                  D          10     5      3    1    slick, oily, thin                                                             uniform fluid, one                                                            phase                                      E          16     12     7    3    same as D                                  F          4      2      1    0    non-uniform,                                                                  watery fluid with                                                             undispersed clumps                                                            of material.sup.1, two                                                        phase                                      G          3      1      0.5  0    same as F                                  H          2      1      0.5  0    same as F                                  I          2      1      0.5  0    same as F                                  J          2      1      0    0    same as F                                  ______________________________________                                    

Footnote: 1. Referred to in the art as a "fish-eye," an agglomerationconsisting of a polymer mass wetted on the exterior, having dry,unsolvated material on the interior.

From the above it is seen that the composition of this invention, whenmixed with water, produces a uniform, one phase fluid, having noundispersed masses of material, a viscosity greater than that of waterand consist of, at least one solvatable, organic polymeric material anda soluble alkaline material.

Example 3

A large volume of dirt had apparently washed out from underneath aportion of the concrete floor of an industrial plant, thereby producinga void space under the floor. The plant owner estimated that 500 cubicyards of material would be required to fill the void and, further,wanted the placement of the material to be performed withoutinterrupting the operation of the plant. A cement slurry pumping methodwas, therefore, indicated in order to comply with the owner's wishes.However, the material specified for placement in the void was a concreteslurry which did not contain sufficient hydraulic cement to enablepumping by employing conventional methods.

The recipe specified by the owner to produce 1 cubic yard of concreteslurry is set out below:

Portland cement, ASTM Type I ...... 100 pounds

Coarse aggregate . . . 0 pounds

Fine aggregate . . . 2700 pounds

Class C Fly Ash . . . 300 pounds

Water . . . 300 pounds

Air entraining additive . . . 10 fluid ounces (aqueous dispersion ofVinsol resin, a registered trademark of Hercules, Incorporated)

The above concrete slurry, which had a design compressive strength aftersetting of about 100 psi, is referred to in the art as a "flowable fill"and also as a "controlled density, low strength material." It isbelieved that a concrete slurry having a design compressive strengthafter setting of less than about 500 psi cannot be pumped and one havinga design compressive strength after setting of between about 500 and2500 psi is extremely difficult to pump.

The alternative to placing the flowable fill by means other than bypumping involved drilling holes through the plant floor to establishcommunication with the void, transporting the slurry by means of buggiesover the plant floor to the holes and then placing the slurry throughthe holes. This process consumed seven days at eight to ten hours perday with consequent disruption in plant operations.

The flowable fill, as described above, was enabled to be pumped by useof the composition of this invention. In this regard, the flowable fillwas prepared at a remote location in batches of eight to ten cubic yardsand transported to the location of the concrete pump by conventionalready mix trucks. To each ready mix load of flowable fill there wasadded a quantity of the pumping aid of this invention as defined inTable IV, Composition B. As stated in Example 2, the pumping aid addedto each batch was entirely contained in water soluble bags. Each Bagcontained 0.5 pounds of the composition of this invention, wherein onebag was added per each two cubic yards of flowable fill in each readymix load. Accordingly, four bags (2 pounds) were added to an eight cubicyard load (27,200 pounds) and five bags (2.5 pounds) were added to a tencubic yard load (34,000 pounds). The contents of each bag weresufficiently dispersed thoughout the batch by normal operation of theconventional mixing means on the ready mix truck.

The entire 500 cubic yards of flowable fill was pumped in six hours. Theoperation of the plant was not interrupted.

Having thus described the invention, that which is claimed is:
 1. Anadditive for a concrete slurry said additive being comprised of a watersoluble, inorganic, alkaline material and a solvatable, organicpolymeric material,wherein the concentration of said alkaline materialin said additive is an amount in the range of from about 40 to about 99parts per 100 parts by weight of said additive and the concentration ofsaid polymeric material in said additive is an amount in the range offrom about 1 to about 60 parts per 100 parts by weight of said additive,and further wherein said organic polymeric material consists essentiallyof a mixture of at least one synthetic hydrophilic polymer and amaterial selected from the group consisting of natural polymers modifiedby reaction with hydrophilic constituents and mixtures thereof, andstill further wherein the weight ratio of said synthetic hydrophilicpolymer to said modified natural polymer is an amount in the range offrom about 1 to 1 to about 2 to 1 and the molecular weight of saidmodified natural polymer is less than about 100,000.
 2. The additive ofclaim 1 wherein said concentration of said alkaline material is in therange of from about 60 to about 90 and the concentration of saidpolymeric material is in the range of from about 10 to about
 40. 3. Theadditive of claim 2 wherein said concentration of said alkaline materialis in the range of from about 70 to about 85 and said concentration ofsaid polymeric material is in the range of from about 15 to about
 30. 4.The additive of claim 2 further including water added thereto in anamount sufficient to dissolve said alkaline material and solvate saidpolymeric material.
 5. The additive of claim 4 wherein said water ispresent in an amount in the range of from about 27 to about 210 poundsof water per pound of said additive.
 6. The additive of claim 1 whereinsaid organic polymeric material is selected from high molecular weight,polymers which disperse in the presence of water to produce an increasein the viscosity of said water, and wherein said alkaline material isselected from the group consisting of alkali metal hydroxides,carbonates bicarbonates and mixtures thereof.
 7. The additive of claim 2wherein said modified natural polymers are selected from the groupconsisting of cellulose derivatives and galactomannan gums andglucomannan gums which have been modified by reaction with hydrophilicconstituents and mixtures thereof, and said alkaline material is analkali metal carbonate.
 8. The additive of claim 3 wherein said naturalpolymers modified by reaction with hydrophilic constituents arecellulose derivatives selected from the group consisting ofhydroxyethylcellulose, carboxymethylcellulose and mixtures thereof, saidsynthetic hydrophilic polymer is polyethylene oxide, and said alkalimetal carbonate is sodium carbonate.
 9. The additive of claim 8 whereinsaid cellulose derivative is hydroxyethylcellulose present in saidadditive in the amount of 6.25 pounds per 100 pounds of said additive,said pelyethylene oxide is present in said additive in the amount of9.375 pounds per 100 pounds of said additive and said sodium carbonateis present in said additive in the amount of 84.375 pounds per 100pounds of said additive.
 10. The additive of claim 1, wherein saidsynthetic hydrophilic polymer is polyacrylamide and wherein said naturalpolymer modified by reaction with hydrophilic constituents ishydroxyethylcellulose.